RESUMEN
Physical exercise is a robust lifestyle intervention known for its enhancement of cognitive abilities. Nevertheless, the extent to which these benefits can be transmitted across generations (intergenerational inheritance to F1, and transgenerational to F2 and beyond) remains a topic of limited comprehension. We have already shown that cognitive improvements resulting from physical exercise can be inherited from parents to their offspring, proving intergenerational effects. So, we set out to explore whether these enhancements might extend transgenerationally, impacting the F2 generation. In this study, we initially examined the behavioral traits of second generation (F2) male mice, whose grandfathers (F0) had an exercise intervention. Our findings revealed that F2 mice with physically active grandpaternal F0 progenitors displayed significantly improved memory recall, encompassing both spatial and non-spatial information when compared to their counterparts from sedentary F0 progenitors, and proving for the first time the transgenerational inheritance of physical exercise induced cognitive enhancement. Surprisingly, while F2 memory improved (as was the case with F1), adult hippocampal neurogenesis remained unchanged between experimental and control groups (unlike in F1). Additionally, our analysis of small RNA sequences in the hippocampus identified 35 differentially expressed miRNAs linked to important brain function categories. Notably, two of these miRNAs, miRNA-144 and miRNA-298, displayed a robust negative correlation with cognitive performance. These findings highlight the enduring transgenerational transmission of cognitive benefits associated with exercise, even after two generations, suggesting that moderate exercise training can have lasting positive effects, possibly orchestrated by a specific set of miRNAs that exert their influence across multiple generations.
Asunto(s)
Cognición , Hipocampo , Condicionamiento Físico Animal , Animales , Masculino , Ratones , Cognición/fisiología , Condicionamiento Físico Animal/fisiología , Hipocampo/fisiología , Hipocampo/metabolismo , Femenino , Neurogénesis/fisiología , Ratones Endogámicos C57BL , MicroARNs/metabolismo , MicroARNs/genéticaRESUMEN
Despite decades of intense research, disease-modifying therapeutic approaches for Alzheimer's disease (AD) are still very much needed. Apart from the extensively analyzed tau and amyloid pathological cascades, two promising avenues of research that may eventually identify new druggable targets for AD are based on a better understanding of the mechanisms of resilience and vulnerability to this condition. We argue that insulin-like growth factor I (IGF-I) activity in the brain provides a common substrate for the mechanisms of resilience and vulnerability to AD. We postulate that preserved brain IGF-I activity contributes to resilience to AD pathology as this growth factor intervenes in all the major pathological cascades considered to be involved in AD, including metabolic impairment, altered proteostasis, and inflammation, to name the three that are considered to be the most important ones. Conversely, disturbed IGF-I activity is found in many AD risk factors, such as old age, type 2 diabetes, imbalanced diet, sedentary life, sociality, stroke, stress, and low education, whereas the Apolipoprotein (Apo) E4 genotype and traumatic brain injury may also be influenced by brain IGF-I activity. Accordingly, IGF-I activity should be taken into consideration when analyzing these processes, while its preservation will predictably help prevent the progress of AD pathology. Thus, we need to define IGF-I activity in all these conditions and develop a means to preserve it. However, defining brain IGF-I activity cannot be solely based on humoral or tissue levels of this neurotrophic factor, and new functionally based assessments need to be developed.
Asunto(s)
Enfermedad de Alzheimer , Factor I del Crecimiento Similar a la Insulina , Humanos , Enfermedad de Alzheimer/metabolismo , Apolipoproteína E4/metabolismo , Encéfalo/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Factor I del Crecimiento Similar a la Insulina/metabolismo , AnimalesRESUMEN
Increased neurotrophic support, including insulin-like growth factor I (IGF-I), is an important aspect of the adaptive response to ischemic insult. However, recent findings indicate that the IGF-I receptor (IGF-IR) in neurons plays a detrimental role in the response to stroke. Thus, we investigated the role of astrocytic IGF-IR on ischemic insults using tamoxifen-regulated Cre deletion of IGF-IR in glial fibrillary acidic protein (GFAP) astrocytes, a major cellular component in the response to injury. Ablation of IGF-IR in astrocytes (GFAP-IGF-IR KO mice) resulted in larger ischemic lesions, greater blood-brain-barrier disruption and more deteriorated sensorimotor coordination. RNAseq detected increases in inflammatory, cell adhesion and angiogenic pathways, while the expression of various classical biomarkers of response to ischemic lesion were significantly increased at the lesion site compared to control littermates. While serum IGF-I levels after injury were decreased in both control and GFAP-IR KO mice, brain IGF-I mRNA expression show larger increases in the latter. Further, greater damage was also accompanied by altered glial reactivity as reflected by changes in the morphology of GFAP astrocytes, and relative abundance of ionized calcium binding adaptor molecule 1 (Iba 1) microglia. These results suggest a protective role for astrocytic IGF-IR in the response to ischemic injury.
RESUMEN
Neural stem cells (NSCs) in the olfactory bulb (OB) core can generate mature interneurons in the adult mice brain. The vast majority of these adult generated cells express the calcium-binding protein Calretinin (CalR), and they migrate towards different OB layers. However, these cells have yet to be fully characterized and hence, to achieve this we injected retroviral particles expressing GFP into the OB core of adult animals and found that the CalR+ neurons generated from NSCs mainly migrate to the granule cell layer (GCL) and glomerular layer (GL) in similar proportions. In addition, since morphology and function are closely related, we used three-dimensional imaging techniques to analyze the morphology of these adult born cells, describing new subtypes of CalR+ interneurons based on their dendritic arborizations and projections, as well as their localization in the GCL or GL. We also show that the migration and morphology of these newly generated neurons can be altered by misexpressing the transcription factor Tbr1 in the OB core. Therefore, the morphology acquired by neurons located in a specific OB layer is the result of a combination of both extrinsic (e.g., layer allocation) and intrinsic mechanisms (e.g., transcription factors). Defining the cellular processes and molecular mechanisms that govern adult neurogenesis might help better understand brain circuit formation and plasticity, as well as eventually opening the way to develop strategies for brain repair.
RESUMEN
Changes in the transcription factor (TF) expression are critical for brain development, and they may also underlie neurodevelopmental disorders. Indeed, T-box brain1 (Tbr1) is a TF crucial for the formation of neocortical layer VI, and mutations and microdeletions in that gene are associated with malformations in the human cerebral cortex, alterations that accompany autism spectrum disorder (ASD). Interestingly, Tbr1 upregulation has also been related to the occurrence of ASD-like symptoms, although limited studies have addressed the effect of increased Tbr1 levels during neocortical development. Here, we analysed the impact of Tbr1 misexpression in mouse neural progenitor cells (NPCs) at embryonic day 14.5 (E14.5), when they mainly generate neuronal layers II-IV. By E18.5, cells accumulated in the intermediate zone and in the deep cortical layers, whereas they became less abundant in the upper cortical layers. In accordance with this, the proportion of Sox5+ cells in layers V-VI increased, while that of Cux1+ cells in layers II-IV decreased. On postnatal day 7, fewer defects in migration were evident, although a higher proportion of Sox5+ cells were seen in the upper and deep layers. The abnormal neuronal migration could be partially due to the altered multipolar-bipolar neuron morphologies induced by Tbr1 misexpression, which also reduced dendrite growth and branching, and disrupted the corpus callosum. Our results indicate that Tbr1 misexpression in cortical NPCs delays or disrupts neuronal migration, neuronal specification, dendrite development and the formation of the callosal tract. Hence, genetic changes that provoke ectopic Tbr1 upregulation during development could provoke cortical brain malformations.
Asunto(s)
Trastorno del Espectro Autista , Neocórtex , Animales , Trastorno del Espectro Autista/genética , Corteza Cerebral/metabolismo , Humanos , Ratones , Neocórtex/metabolismo , Neurogénesis/genética , Neuronas/metabolismo , Proteínas de Dominio T Box/genética , Proteínas de Dominio T Box/metabolismo , Factores de Transcripción/metabolismoRESUMEN
Mice with insulin receptor (IR)-deficient astrocytes (GFAP-IR knockout [KO] mice) show blunted responses to insulin and reduced brain glucose uptake, whereas IR-deficient astrocytes show disturbed mitochondrial responses to glucose. While exploring the functional impact of disturbed mitochondrial function in astrocytes, we observed that GFAP-IR KO mice show uncoupling of brain blood flow with glucose uptake. Since IR-deficient astrocytes show higher levels of reactive oxidant species (ROS), this leads to stimulation of hypoxia-inducible factor-1α and, consequently, of the vascular endothelial growth factor angiogenic pathway. Indeed, GFAP-IR KO mice show disturbed brain vascularity and blood flow that is normalized by treatment with the antioxidant N-acetylcysteine (NAC). NAC ameliorated high ROS levels, normalized angiogenic signaling and mitochondrial function in IR-deficient astrocytes, and normalized neurovascular coupling in GFAP-IR KO mice. Our results indicate that by modulating glucose uptake and angiogenesis, insulin receptors in astrocytes participate in neurovascular coupling.
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Astrocitos , Encéfalo , Insulina , Neovascularización Fisiológica , Acoplamiento Neurovascular , Animales , Astrocitos/metabolismo , Encéfalo/irrigación sanguínea , Proteína Ácida Fibrilar de la Glía/genética , Glucosa/metabolismo , Insulina/metabolismo , Ratones , Ratones Noqueados , Especies Reactivas de Oxígeno/metabolismo , Receptor de Insulina/genética , Factor A de Crecimiento Endotelial Vascular/genética , Factor A de Crecimiento Endotelial Vascular/metabolismoRESUMEN
Sleep disturbances are common during aging. Compared to young animals, old mice show altered sleep structure, with changes in both slow and fast electrocorticographic (ECoG) activity and fewer transitions between sleep and wake stages. Insulin-like growth factor I (IGF-I), which is involved in adaptive changes during aging, was previously shown to increase ECoG activity in young mice and monkeys. Furthermore, IGF-I shapes sleep architecture by modulating the activity of mouse orexin neurons in the lateral hypothalamus (LH). We now report that both ECoG activation and excitation of orexin neurons by systemic IGF-I are abrogated in old mice. Moreover, orthodromical responses of LH neurons are facilitated by either systemic or local IGF-I in young mice, but not in old ones. As orexin neurons of old mice show dysregulated IGF-I receptor (IGF-IR) expression, suggesting disturbed IGF-I sensitivity, we treated old mice with AIK3a305, a novel IGF-IR sensitizer, and observed restored responses to IGF-I and rejuvenation of sleep patterns. Thus, disturbed sleep structure in aging mice may be related to impaired IGF-I signaling onto orexin neurons, reflecting a broader loss of IGF-I activity in the aged mouse brain.
Asunto(s)
Área Hipotalámica Lateral , Factor I del Crecimiento Similar a la Insulina , Animales , Ratones , Orexinas/metabolismo , Factor I del Crecimiento Similar a la Insulina/metabolismo , Área Hipotalámica Lateral/metabolismo , Sueño/fisiología , Neuronas/metabolismoRESUMEN
Uncoupling of metabolism and circadian activity is associated with an increased risk of a wide spectrum of pathologies. Recently, insulin and the closely related insulin-like growth factor I (IGF-I) were shown to entrain feeding patterns with circadian rhythms. Both hormones act centrally to modulate peripheral glucose metabolism; however, whereas central targets of insulin actions are intensely scrutinized, those mediating the actions of IGF-I remain less defined. We recently showed that IGF-I targets orexin neurons in the lateral hypothalamus, and now we evaluated whether IGF-I modulates orexin neurons to align circadian rhythms with metabolism. Mice with disrupted IGF-IR activity in orexin neurons (Firoc mice) showed sexually dimorphic alterations in daily glucose rhythms and feeding activity patterns which preceded the appearance of metabolic disturbances. Thus, Firoc males developed hyperglycemia and glucose intolerance, while females developed obesity. Since IGF-I directly modulates orexin levels and hepatic expression of KLF genes involved in circadian and metabolic entrainment in an orexin-dependent manner, it seems that IGF-I entrains metabolism and circadian rhythms by modulating the activity of orexin neurons.
Asunto(s)
Ritmo Circadiano , Hipotálamo , Factor I del Crecimiento Similar a la Insulina , Animales , Ritmo Circadiano/genética , Ritmo Circadiano/fisiología , Femenino , Hipotálamo/metabolismo , Insulina/metabolismo , Factor I del Crecimiento Similar a la Insulina/genética , Factor I del Crecimiento Similar a la Insulina/metabolismo , Masculino , Ratones , Neuronas/metabolismo , Orexinas/metabolismoRESUMEN
Maladaptive coping behaviors are probably involved in post-traumatic stress disorders (PTSD), but underlying mechanisms are incompletely understood. We now report that mice lacking functional insulin-like growth factor I (IGF-I) receptors in orexin neurons of the lateral hypothalamus (Firoc mice) are unresponsive to the anxiolytic actions of IGF-I and develop PTSD-like behavior that is ameliorated by inhibition of orexin neurons. Conversely, systemic IGF-I treatment ameliorated PTSD-like behavior in a wild-type mouse model of PTSD (PTSD mice). Further, systemic IGF-I modified the GABA/Glutamate synaptic structure in orexin neurons of naïve wild-type mice by increasing the dephosphorylation of GABA(B) receptor subunit through inhibition of AMP-kinase (AMPK). Significantly, pharmacological inhibition of AMPK mimicked IGF-I, normalizing fear behavior in PTSD mice. Thus, we suggest that IGF-I enables coping behaviors by balancing E/I input onto orexin neurons in a context-dependent manner. These observations provide a novel therapeutic approach to PTSD through modulation of AMPK.
Asunto(s)
Factor I del Crecimiento Similar a la Insulina , Trastornos por Estrés Postraumático , Proteínas Quinasas Activadas por AMP , Adenosina Monofosfato/metabolismo , Adenosina Monofosfato/uso terapéutico , Adenilato Quinasa/metabolismo , Animales , Factor I del Crecimiento Similar a la Insulina/metabolismo , Ratones , Neuronas/metabolismo , Orexinas/metabolismo , Trastornos por Estrés Postraumático/tratamiento farmacológico , Trastornos por Estrés Postraumático/metabolismo , Ácido gamma-Aminobutírico/metabolismoRESUMEN
Insulin-like growth factor-I (IGF-I) signaling plays a key role in learning and memory processes. While the effects of IGF-I on neurons have been studied extensively, the involvement of astrocytes in IGF-I signaling and the consequences on synaptic plasticity and animal behavior remain unknown. We have found that IGF-I induces long-term potentiation (LTPIGFI) of the postsynaptic potentials that is caused by a long-term depression of inhibitory synaptic transmission in mice. We have demonstrated that this long-lasting decrease in the inhibitory synaptic transmission is evoked by astrocytic activation through its IGF-I receptors (IGF-IRs). We show that LTPIGFI not only increases the output of pyramidal neurons, but also favors the NMDAR-dependent LTP, resulting in the crucial information processing at the barrel cortex since specific deletion of IGF-IR in cortical astrocytes impairs the whisker discrimination task. Our work reveals a novel mechanism and functional consequences of IGF-I signaling on cortical inhibitory synaptic plasticity and animal behavior, revealing that astrocytes are key elements in these processes.SIGNIFICANCE STATEMENT Insulin-like growth factor-I (IGF-I) signaling plays key regulatory roles in multiple processes of brain physiology, such as learning and memory. Yet, the underlying mechanisms remain largely undefined. Here we demonstrate that astrocytes respond to IGF-I signaling, elevating their intracellular Ca2+ and stimulating the release of ATP/adenosine, which triggers the LTD of cortical inhibitory synapses, thus regulating the behavioral task performance related to cortical sensory information processing. Therefore, the present work represents a major conceptual advance in our knowledge of the cellular basis of IGF-I signaling in brain function, by including for the first time astrocytes as key mediators of IGF-I actions on synaptic plasticity, cortical sensory information discrimination and animal behavior.
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Adenosina/metabolismo , Astrocitos/metabolismo , Plasticidad Neuronal/fisiología , Receptor IGF Tipo 1/metabolismo , Corteza Somatosensorial/fisiología , Animales , Conducta Animal/fisiología , Regulación hacia Abajo , Aprendizaje/fisiología , Depresión Sináptica a Largo Plazo/fisiología , Masculino , Memoria/fisiología , Ratones , Ratones Endogámicos C57BL , Células Piramidales/fisiologíaRESUMEN
Obesity is a risk factor for Alzheimer's disease (AD), but underlying mechanisms are not clear. We analyzed peripheral clearance of amyloid ß (Aß) in overweight mice because its systemic elimination may impact brain Aß load, a major landmark of AD pathology. We also analyzed whether circulating insulin-like growth factor I (IGF-I) intervenes in the effects of overweight as this growth factor modulates brain Aß clearance and is increased in the serum of overweight mice. Overweight mice showed increased Aß accumulation by the liver, the major site of elimination of systemic Aß, but unaltered brain Aß levels. We also found that Aß accumulation by hepatocytes is stimulated by IGF-I, and that mice with low serum IGF-I levels show reduced liver Aß accumulation-ameliorated by IGF-I administration, and unchanged brain Aß levels. In the brain, IGF-I favored the association of its receptor (IGF-IR) with the Aß precursor protein (APP), and at the same time, stimulated non-amyloidogenic processing of APP in astrocytes, as indicated by an increased sAPPα/sAPPß ratio after IGF-I treatment. Since serum IGF-I enters into the brain in an activity-dependent manner, we analyzed in overweight mice the effect of brain activation by environmental enrichment (EE) on brain IGF-IR phosphorylation and its association to APP, as a readout of IGF-I activity. After EE, significantly reduced brain IGF-IR phosphorylation and APP/IGF-IR association were found in overweight mice as compared to lean controls. Collectively, these results indicate that a high-fat diet influences peripheral clearance of Aß without affecting brain Aß load. Increased serum IGF-I likely contributes to enhanced peripheral Aß clearance in overweight mice, without affecting brain Aß load probably because its brain entrance is reduced.
Asunto(s)
Péptidos beta-Amiloides/metabolismo , Dieta Alta en Grasa , Factor I del Crecimiento Similar a la Insulina/metabolismo , Enfermedad de Alzheimer/etiología , Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/patología , Precursor de Proteína beta-Amiloide/metabolismo , Animales , Biomarcadores , Encéfalo/metabolismo , Encéfalo/patología , Modelos Animales de Enfermedad , Hepatocitos/metabolismo , Ratones , Ratones Transgénicos , SobrepesoRESUMEN
Although sleep disturbances are common co-morbidities of metabolic diseases, the underlying processes linking both are not yet fully defined. Changes in the duration of sleep are paralleled by changes in the levels of insulin-like growth factor-I (IGF-I), an anabolic hormone that shows a circadian pattern in the circulation and activity-dependent entrance in the brain. However, the specific role, if any, of IGF-I in this universal homeostatic process remains poorly understood. We now report that the activity of orexin neurons, a discrete cell population in the lateral hypothalamus that is involved in the circadian sleep/wake cycle and arousal, is modulated by IGF-I. Furthermore, mice with blunted IGF-I receptor activity in orexin neurons have lower levels of orexin in the hypothalamus, show altered electro-corticographic patterns with predominant slow wave activity, and reduced onset-sleep latency. Collectively, these results extend the role in the brain of this pleiotropic growth factor to shaping sleep architecture through the regulation of orexin neurons. We speculate that poor sleep quality associated to diverse conditions may be related to disturbed brain IGF-I input to orexin neurons.
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Hipotálamo/metabolismo , Factor I del Crecimiento Similar a la Insulina/metabolismo , Neuronas/metabolismo , Orexinas/metabolismo , Sueño/fisiología , Animales , Ritmo Circadiano/fisiología , Femenino , Hipotálamo/fisiología , Masculino , Ratones , Ratones Endogámicos C57BL , Neuronas/fisiologíaRESUMEN
Proliferative kidney disease (PKD) is a parasitic infection of salmonid fish characterized by hyper-secretion of immunoglobulins in response to the presence of the myxozoan parasite, Tetracapsuloides bryosalmonae. In this context, we hypothesized that the BAFF/APRIL axis, known to play a major role in B cell differentiation and survival in mammals, could be affected by the parasite and consequently be involved in the apparent shift in normal B cell activity. To regulate B cell activity, BAFF and APRIL bind to transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) and B cell maturation antigen (BCMA), whereas BAFF also binds to BAFF receptor (BAFF-R). In teleost fish, although some BAFF and APRIL sequences have been reported, their receptors have not been identified. Thus, as a first step in the current work, we have identified homologues to mammalian TACI, BCMA and BAFF-R in rainbow trout (Oncorhynchus mykiss), that constitute the first report of BAFF and APRIL receptor sequences in fish. Subsequently we studied the transcriptional modulation of BAFF, APRIL, and the fish-specific related cytokine, BALM and their putative receptors in fish naturally exposed to T. bryosalmonae. Finally, to gain further insights on the functional role that these cytokines play during the course of PKD, we have studied their effect on the survival of kidney IgM+ B cells and on immunoglobulin transcription. Our results support the premise that the BAFF / APRIL axis could play an important role during PKD, which may open the possibility of new therapeutic treatments against the disease.
Asunto(s)
Receptor del Factor Activador de Células B/metabolismo , Antígeno de Maduración de Linfocitos B/metabolismo , Enfermedades de los Peces/patología , Enfermedades Renales/patología , Oncorhynchus mykiss/parasitología , Enfermedades Parasitarias en Animales/patología , Proteína Activadora Transmembrana y Interactiva del CAML/metabolismo , Miembro 13 de la Superfamilia de Ligandos de Factores de Necrosis Tumoral/metabolismo , Animales , Linfocitos B/inmunología , Secuencia de Bases , Enfermedades de los Peces/parasitología , Regulación de la Expresión Génica , Enfermedades Renales/parasitología , Myxozoa , Enfermedades Parasitarias en Animales/parasitología , Análisis de Secuencia de ADN , Proteína Activadora Transmembrana y Interactiva del CAML/genéticaRESUMEN
Although fish constitute the most ancient animal group in which an acquired immune system is present, the presence of dendritic cells (DCs) in teleosts has been addressed only briefly, and the identification of a specific DC subset in teleosts remained elusive because of the lack of specific Abs. In mice, DCs expressing CD8α(+) in lymphoid tissues have the capacity to cross-present extracellular Ags to T cells through MHC I, similarly to tissue-derived CD103(+) DCs and the human CD141(+) DC population. In the current study, we identified a large and highly complex subpopulation of leukocytes coexpressing MHC class II and CD8α. This CD8α(+) MHC II(+) DC-like subpopulation constituted â¼1.2% of the total leukocyte population in the skin, showing phenotypical and functional characteristics of semimature DCs that seem to locally regulate mucosal immunity and tolerance in a species lacking lymph nodes. Furthermore, we identified trout homologs for CD141 and CD103 and demonstrated that, in trout, this skin CD8(+) DC-like subpopulation expresses both markers. To our knowledge, these results provide the first evidence of a specific DC-like subtype in nonimmune tissue in teleosts and support the hypothesis of a common origin for all mammalian cross-presenting DCs.
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Antígenos CD8/metabolismo , Reactividad Cruzada/inmunología , Células Dendríticas/inmunología , Células Dendríticas/metabolismo , Células de Langerhans/inmunología , Células de Langerhans/metabolismo , Animales , Antígenos CD/metabolismo , Antígenos de Superficie/metabolismo , Peces , Antígenos de Histocompatibilidad Clase II/inmunología , Humanos , Cadenas alfa de Integrinas/metabolismo , Ratones , Datos de Secuencia Molecular , Fagocitosis , Fenotipo , Filogenia , Proteoma , Proteómica , Piel/inmunología , Piel/metabolismo , Bazo/inmunología , Bazo/metabolismo , Linfocitos T/inmunología , Linfocitos T/metabolismo , Trombomodulina , Receptores Toll-Like/metabolismo , Transcriptoma , Zimosan/inmunologíaRESUMEN
Tetraspanins are a family of membrane-organizing proteins, characterized by the presence of four highly conserved transmembrane regions that mediate diverse physiological functions. In the current study, we have identified two novel tetraspanin members in rainbow trout (Oncorhynchus mykiss), homologs to mammalian CD9 and CD63. Both genes were expressed in muscle, skin, gills, hindgut, gonad, liver, spleen, head kidney, thymus and peripheral blood leukocytes. Throughout the early life cycle stages, CD9 mRNA levels significantly increased after first feeding, whereas CD63 transcription remained constant during all the developmental stages analyzed. In response to an experimental bath infection with viral hemorrhagic septicemia virus (VHSV), CD9 transcription was down-regulated in the gills, while CD63 mRNA levels were down-regulated in the head kidney. Instead, when the virus was intraperitoneally injected, the transcription of both genes was significantly up-regulated in peritoneal cells at several days post-infection. Additionally, both genes were transcriptionally up-regulated in the muscle of trout injected with a VHSV DNA vaccine. To gain insight on the relation of these tetraspanins with B cell activity we determined their constitutive expression in naive IgM(+) populations from different sources and observed that both molecules were being transcribed by IgM(+) cells in different tissues. Furthermore, CD9 transcription was significantly down-regulated in splenic IgM(+) cells in response to in vitro VHSV exposure. Our results provide insights on the potential role of these tetraspanins on teleost B cell and antiviral immunity.
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Linfocitos B/fisiología , Proteínas de Peces/metabolismo , Novirhabdovirus/inmunología , Oncorhynchus mykiss/inmunología , Infecciones por Rhabdoviridae/inmunología , Tetraspanina 29/metabolismo , Tetraspanina 30/metabolismo , Tetraspaninas/metabolismo , Animales , Linfocitos B/virología , Proteínas de Peces/genética , Regulación de la Expresión Génica/inmunología , Inmunidad Humoral , Inmunoglobulina M/metabolismo , Mamíferos , Homología de Secuencia de Aminoácido , Tetraspanina 29/genética , Tetraspanina 30/genética , Tetraspaninas/genética , Transcriptoma , Vacunas Virales/administración & dosificaciónRESUMEN
The transcription factor Nurr1 is expressed in the mouse olfactory bulb (OB), although it remains unknown whether it influences the generation of dopaminergic neurons (DA) (DA neurons) in cells isolated from this brain region. We found that expressing Nurr1 in proliferating olfactory bulb stem cells (OBSCs) produces a marked inhibition of cell proliferation and the generation of immature neurons immunoreactive for tyrosine hydroxylase (TH) concomitant with marked upregulations of Th, Dat, Gad, and Fgfr2 transcripts. In long-term cultures, these cells develop neurochemical and synaptic markers of mature-like mesencephalic DA neurons, expressing GIRK2, VMAT2, DAT, calretinin, calbindin, synapsin-I, and SV2. Concurring with the increase in both Th and Gad expression, a subpopulation of induced cells was both TH- and GAD-immunoreactive indicating that they are dopaminergic-GABAergic neurons. Indeed, these cells could mature to express VGAT, suggesting they can uptake and store GABA in vesicles. Remarkably, the dopamine D1 receptor agonist SKF-38393 induced c-Fos in TH(+) cells and dopamine release was detected in these cultures under basal and KCl-evoked conditions. By contrast, cotransducing the Neurogenin2 and Nurr1 transcription factors produced a significant decrease in the number of TH-positive neurons. Our results indicate that Nurr1 overexpression in OBSCs induces the formation of two populations of mature dopaminergic neurons with features of the ventral mesencephalon or of the OB, capable of responding to functional dopaminergic stimuli and of releasing dopamine. They also suggest that the accumulation of Fgfr2 by Nurr1 in OBSCs may be involved in the generation of DA neurons.
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Neuronas Dopaminérgicas/fisiología , Neuronas GABAérgicas/fisiología , Células-Madre Neurales/fisiología , Neurogénesis/fisiología , Miembro 2 del Grupo A de la Subfamilia 4 de Receptores Nucleares/metabolismo , Bulbo Olfatorio/fisiología , Animales , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Proliferación Celular/efectos de los fármacos , Proliferación Celular/fisiología , Células Cultivadas , Neuronas Dopaminérgicas/efectos de los fármacos , Factor de Crecimiento Epidérmico/metabolismo , Factor 2 de Crecimiento de Fibroblastos/metabolismo , Neuronas GABAérgicas/efectos de los fármacos , Ratones Endogámicos C57BL , Mitosis/efectos de los fármacos , Mitosis/fisiología , Proteínas del Tejido Nervioso/metabolismo , Células-Madre Neurales/efectos de los fármacos , Neurogénesis/efectos de los fármacos , Bulbo Olfatorio/efectos de los fármacos , Tirosina 3-Monooxigenasa/metabolismoRESUMEN
Among the essential metabolic functions of the liver, in mammals, a role as mediator of systemic and local innate immunity has also been reported. Although the presence of an important leukocyte population in mammalian liver is well documented, the characterization of leukocyte populations in the teleost liver has been only scarcely addressed. In the current work, we have confirmed the presence of IgM+, IgD+, IgT+, CD8α+, CD3+ cells, and cells expressing major histocompatibility complex (MHC-II) in rainbow trout (Oncorhynchus mykiss) liver by flow cytometry and/or immunohistochemistry analysis. Additionally, the effect of viral hemorrhagic septicemia virus (VHSV) on the liver immune response was assessed. First, we studied the effect of viral intraperitoneal injection on the transcription of a wide selection of immune genes at days 1, 2 and 5 post-infection. These included a group of leukocyte markers genes, pattern recognition receptors (PRRs), chemokines, chemokine receptor genes, and other genes involved in the early immune response and in acute phase reaction. Our results indicate that T lymphocytes play a key role in the initial response to VHSV in the liver, since CD3, CD8, CD4, perforin, Mx and interferon (IFN) transcription levels were up-regulated in response to VHSV. Consequently, flow cytometry analysis of CD8α+ cells in liver and spleen at day 5 post-infection revealed a decrease in the number of CD8α+ cells in the spleen and an increased population in the liver. No differences were found however in the percentages of B lymphocyte (IgM+ or IgD+) populations. In addition, a strong up-regulation in the transcription levels of several PRRs and chemokines was observed from the second day of infection, indicating an important role of these factors in the response of the liver to viral infections.
Asunto(s)
Enfermedades de los Peces/inmunología , Hígado/inmunología , Novirhabdovirus/inmunología , Oncorhynchus mykiss/inmunología , Infecciones por Rhabdoviridae/veterinaria , Animales , Linfocitos T CD8-positivos/inmunología , Quimiocinas/genética , Quimiocinas/metabolismo , Femenino , Enfermedades de los Peces/metabolismo , Enfermedades de los Peces/virología , Glicoproteínas/genética , Glicoproteínas/metabolismo , Inmunidad Celular , Leucocitos/inmunología , Leucocitos/virología , Hígado/metabolismo , Hígado/patología , Hígado/virología , Oncorhynchus mykiss/metabolismo , Oncorhynchus mykiss/virología , Receptores de Quimiocina/genética , Receptores de Quimiocina/metabolismo , Receptores de Reconocimiento de Patrones/genética , Infecciones por Rhabdoviridae/inmunología , Infecciones por Rhabdoviridae/metabolismo , Infecciones por Rhabdoviridae/virología , Bazo/inmunología , Bazo/patología , Transcripción Genética , Proteínas Virales/genética , Proteínas Virales/metabolismoRESUMEN
The immune response of the adipose tissue (AT) has been neglected in most animal models until recently, when the observations made in human and mice linking obesity to chronic inflammation and diabetes highlighted an important immune component of this tissue. In the current study, we have immunologically characterized the AT for the first time in teleosts. We have analyzed the capacity of rainbow trout (Oncorhynchus mykiss) AT to produce different immune mediators and we have identified the presence of local populations of B lymphocytes expressing IgM, IgD or IgT, CD8α+ cells and cells expressing major histocompatibility complex II (MHC-II). Because trout AT retained antigens from the peritoneal cavity, we analyzed the effects of intraperitoneal infection with viral hemorrhagic septicemia virus (VHSV) on AT functionality. A wide range of secreted immune factors were modulated within the AT in response to VHSV. Furthermore, the viral infection provoked a significant decrease in the number of IgM+ cells which, along with an increased secretion of IgM in the tissue, suggested a differentiation of B cells into plasmablasts. The virus also increased the number of CD8α+ cells in the AT. Finally, when a fat-enriched diet was fed to the fish, a significant modulation of immune gene expression in the AT was also observed. Thus, we have demonstrated for the first time in teleost that the AT functions as a relevant immune tissue; responsive to peritoneal viral infections and that this immune response can be modulated by the fat-content in the diet.
Asunto(s)
Tejido Adiposo/inmunología , Linfocitos B/inmunología , Diferenciación Celular/inmunología , Oncorhynchus mykiss/inmunología , Tejido Adiposo/metabolismo , Tejido Adiposo/patología , Animales , Linfocitos B/metabolismo , Dieta , Humanos , Inmunoglobulina M/inmunología , Inmunoglobulina M/metabolismo , Factores Inmunológicos/metabolismo , Ratones , Novirhabdovirus/inmunología , Novirhabdovirus/patogenicidad , Transcripción Genética/inmunologíaRESUMEN
Chemokine receptor CCR7, the receptor for both CCL19 and CCL21 chemokines, regulates the recruitment and clustering of circulating leukocytes to secondary lymphoid tissues, such as lymph nodes and Peyer's patches. Even though teleost fish do not have either of these secondary lymphoid structures, we have recently reported a homolog to CCR7 in rainbow trout (Oncorhynchus mykiss). In the present work, we have studied the distribution of leukocytes bearing extracellular CCR7 in naive adult tissues by flow cytometry, observing that among the different leukocyte populations, the highest numbers of cells with membrane (mem)CCR7 were recorded in the gill (7.5 ± 2% CCR7(+) cells). In comparison, head kidney, spleen, thymus, intestine, and peripheral blood possessed <5% CCR7(+) cells. When CCR7 was studied at early developmental stages, we detected a progressive increase in gene expression and protein CCR7 levels in the gills throughout development. Surprisingly, the majority of the CCR7(+) cells in the gills were not myeloid cells and did not express membrane CD8, IgM, nor IgT, but expressed IgD on the cell surface. In fact, most IgD(+) cells in the gills expressed CCR7. Intriguingly, the IgD(+)CCR7(+) population did not coexpress memIgM. Finally, when trout were bath challenged with viral hemorrhagic septicemia virus, the number of CCR7(+) cells significantly decreased in the gills while significantly increased in head kidney. These results provide evidence of the presence of a novel memIgD(+)memIgM(-) B lymphocyte subset in trout that expresses memCCR7 and responds to viral infections. Similarities with IgD(+)IgM(-) subsets in mammals are discussed.
Asunto(s)
Subgrupos de Linfocitos B/metabolismo , Regulación del Desarrollo de la Expresión Génica , Branquias/metabolismo , Inmunoglobulina D/análisis , Oncorhynchus mykiss/metabolismo , Receptores CCR7/biosíntesis , Animales , Especificidad de Anticuerpos , Femenino , Branquias/citología , Branquias/crecimiento & desarrollo , Riñón Cefálico/citología , Riñón Cefálico/crecimiento & desarrollo , Riñón Cefálico/metabolismo , Septicemia Hemorrágica Viral/inmunología , Inmunoglobulina M/análisis , Tejido Linfoide/citología , Tejido Linfoide/crecimiento & desarrollo , Tejido Linfoide/metabolismo , Novirhabdovirus/fisiología , Oncorhynchus mykiss/genética , Oncorhynchus mykiss/crecimiento & desarrollo , Oncorhynchus mykiss/inmunología , Especificidad de Órganos , Receptores CCR7/genética , Receptores CCR7/inmunologíaRESUMEN
TWO major classes of b lymphocytes have been described to date in rainbow trout: IgM(+) and IgT(+) cells. IgM(+) cells are mainly localized in the spleen, peripheral blood and kidney but are also found in other tissues. However, differences among IgM(+) cell populations attending to its location are poorly defined in fish. Thus, the aim of this work was to characterize the expression of different immune molecules such as chemokine receptors, Toll-like receptors (TLRs) and transcription factors on sorted IgM(+) lymphocytes from different rainbow trout tissues. IgM(+) populations from blood, spleen, kidney, gills, intestine and liver were isolated by cell sorting and the constitutive levels of transcription of these genes evaluated by real-time PCR. To further characterize B cells, we identified an MS4A sequence. In humans, the MS4A family includes several genes with immune functions, such as the B cell marker CD20 or FcRß. Subsequently, we have also evaluated the mRNA levels of this MS4A gene in the different IgM(+) populations. The relevant differences in transcriptional patterns observed for each of these IgM(+) populations analyzed, point to the presence of functionally different tissue-specific B cell populations in rainbow trout. The data shown provides a pattern of genes transcribed in IgM(+) B cells not previously revealed in teleost fish. Furthermore, the constitutive expression of all the TLR genes analyzed in IgM(+) cells suggests an important role for these cells in innate immunity.